This Core will focus on the role of genetic susceptibility in toxic responses to environmental agents. Its stated long-range goal is, "to identify and characterize genetic polymorphisms concerning differences in response to environmental agents - responses include tumorigenesis as well as acute and chronic toxicity." There are six specific aims stated for this Research Core: 1) to elucidate mechanisms of gene expression and regulation through genetic variants; 2) to screen populations and three- generation families for differences in toxic responses; 3) to determine associations between a genetic locus and a phenotypic trait; 4) to understand the molecular basis of a polymorphism; 5) to study the interaction of genes and agents during embryogenesis; and 6) to evaluate the impact of each polymorphism on human health.